1. Field of the Invention
This invention relates to an X-ray machine and also to a method for monitoring a diathermy treatment. In particular, the invention relates to an X-ray machine for imaging a breast of a female patient (mammography), and also a method for monitoring diathermy treatment of a breast tumor.
2. Description of Related Art
Various X-ray machines are used for performing an examination of a female breast. One type of X-ray machine comprises a rotating gantry, having an X-ray tube and an X-ray detector, located below a patient's table on which a patient to be examined rests. An embodiment of such an X-ray machine is disclosed, for example, in U.S. Pat. No. 4,015,836. The X-ray machine disclosed in U.S. Pat. No. 4,015,836 facilitates diagnosis of diseases of the breast, in particular, of tumors in the breast. The tumors detected by the X-ray machine may be treated in various ways. A proven treatment method is that of hyperthermy. In this treatment method, tissue in a vicinity of the tumor is heated so strongly that the cells of the tumor die away.
An embodiment of a hyperthermy instrument is disclosed in U.S. Pat. No. 6,358,246. An electrode of the hyperthermy instrument is introduced into the tumor to treat the tumor. Once inserted, the electrode is used to pass a high-frequency current through the tissue of the tumor. A rise of electrical impedance of the tissue is made use of here as a measure of maximum power. However, heating of the tumor cannot be controlled in a precise manner, because the temperature of the tissue is not directly related to the current flow or the energy introduced into the tissue by the electrode. Controlled therapy of a tumor is, therefore, difficult with an instrument of this kind.
U.S. Pat. No. 6,684,097 discloses a method for temperature monitoring during diathermy treatment of a breast. This method produces and stores a high-resolution three-dimensional X-ray exposure or photograph of a breast before treatment. During the treatment, further high-resolution three-dimensional photographs of the breast are produced and compared with the original exposure. The method compares the exposures taken before and during treatment, and from a difference between individual pixel values, draws conclusions about a temperature change. A disadvantage of this method is the high radiation load caused during the high-resolution three-dimensional exposures.